Dosimetric Comparision of Coplanar versus Noncoplanar Volumetric Modulated Arc Therapy for Treatment of Bilateral Breast Cancers.

Introduction: The purpose of this study was to compare the dosimetric parameters of volumetric modulated arc therapy (VMAT) treatment plans using coplanar and noncoplanar beams in patients with bilateral breast cancer/s (BBCs) in terms of organ at risk sparing and target volume coverage. The hypothesis was to test whether VMAT with noncoplanar beams can result in lesser dose delivery to critical organs such as heart and lung, which will result in lesser overall toxicity. Materials and Methods: Data of nine BBC cases treated at our hospital were retrieved. Computed tomography simulation data of these cases was used to generate noncoplanar VMAT plans and the parameters were compared with standard VMAT coplanar plans. Contouring was done using radiation therapy oncology group guidelines. Forty-five Gray in 25 fractions was planned followed by 10 Gy in five fractions boost in breast conservation cases. Results: No significant difference in planning target volume (PTV) coverage was found for the right breast/chestwall (P = 0.940), left breast/chestwall (P = 0.872), and in the total PTV (P = 0.929). Noncoplanar beams resulted in better cardiac sparing in terms of Dmean heart. The difference in mean dose was >1 Gy (8.80 ± 0.28 - 7.28 ± 0.33, P < 0.001). The Dmean, V20 and V30 values for total lung slightly favor noncoplanar beams, although there was no statistically significant difference. The average monitor units (MUs) were similar for coplanar plans (1515 MU) and noncoplanar plans (1455 MU), but the overall treatment time was higher in noncoplanar plans due to more complex setup and beam arrangement. For noncoplanar VMAT plans, the mean conformity index was slightly better although the homogeneity indices were similar. Conclusion: VMAT plans with noncoplanar beam arrangements had significant dosimetric advantages in terms of sparing of critical organs, that is Dmean of heart doses with almost equivalent lung doses and equally good target coverage. Larger studies with clinical implications need to be considered to validate this data.

Arbuscular Mycorrhizal Fungi Regulate Polyamine Homeostasis in Roots of Trifoliate Orange for Improved Adaptation to Soil Moisture Deficit Stress.

Soil arbuscular mycorrhizal fungi (AMF) enhance the tolerance of plants against soil moisture deficit stress (SMDS), but the underlying mechanisms are still not fully understood. Polyamines (PAs) as low-molecular-weight, aliphatic polycations have strong roles in abiotic stress tolerance of plants. We aimed to investigate the effect of AMF (Funneliformis mosseae) inoculation on PAs, PA precursors, activities of PA synthases and degrading enzymes, and concentration of reactive oxygen species in the roots of trifoliate orange (Poncirus trifoliata) subjected to 15 days of SMDS. Leaf water potential and total chlorophyll levels were comparatively higher in AMF-inoculated than in non-AMF-treated plants exposed to SMDS. Mycorrhizal plants recorded a significantly higher concentration of precursors of PA synthesis such as L-ornithine, agmatine, and S-adenosyl methionine, besides higher putrescine and cadaverine and lower spermidine during the 15 days of SMDS. AMF colonization raised the PA synthase (arginine decarboxylase, ornithine decarboxylase, spermidine synthase, and spermine synthase) activities and PA-degrading enzymes (copper-containing diamine oxidase and FAD-containing polyamine oxidase) in response to SMDS. However, mycorrhizal plants showed a relatively lower degree of membrane lipid peroxidation, superoxide anion free radical, and hydrogen peroxide than non-mycorrhizal plants, whereas the difference between them increased linearly up to 15 days of SMDS. Our study concluded that AMF regulated PA homeostasis in roots of trifoliate orange to tolerate SMDS.

Evaluation of purely accelerated six fractions per week radiotherapy in postoperative oral cavity squamous cell carcinoma.

OBJECTIVES: Randomized controlled trials have shown improved loco-regional control (LRC) and disease-free survival (DFS) by modest acceleration using six fractions per-week radiotherapy (RT) as compared to conventional fractionation in patients of head and neck squamous cell carcinoma. We aimed to evaluate the role of pure modestly accelerated fractionated radiotherapy (PM-ART) using six fractions per-week in patients of postoperative oral cavity squamous cell carcinoma (OCSCC). MATERIALS AND METHODS: Between May 2015 and July 2016, 40 OCSCC patients with ≥ 1 indication of RT were treated with adjuvant PM-ART, 60 Gray in 30 fractions over 5 weeks by three-dimensional conformal technique on a linear accelerator with a sixth 2 Gray fraction on Saturday using same fields. Primary endpoint was to assess acute toxicity, which was reviewed weekly during RT using Radiation Therapy Oncology Group criteria. RESULTS: Maximal grade 3 oral mucositis, pharynx/esophageal toxicity, and skin toxicity were seen in 77.5%, 25%, and 17.5%, respectively. Two patients had grade 4 mucositis. 47.5% were on tube feeding during RT. All the patients were taken off Ryle's tube within 4 weeks of RT completion. The median RT completion duration was 36 days. Three patients had treatment interruptions. With a median follow-up of 21.2 months, the 2-year LRC, DFS, and overall survival rates were 87.5%, 83.5%, and 85%, respectively. There were two distant failures. CONCLUSION: PM-ART is feasible and tolerable. The high acute mucositis rates did not result in increased consequential late toxicity.

Evaluation of XRCC1 Gene Polymorphism as a Biomarker in Head and Neck Cancer Patients Undergoing Chemoradiation Therapy.

PURPOSE: We evaluated the correlation of the x-ray repair cross complementing gene 1 (XRCC1) Arg194Trp polymorphism with clinical outcomes in head and neck squamous cell carcinoma (HNSCC) patients treated with concurrent chemoradiation therapy (CCRT). METHODS AND MATERIALS: In this prospective cohort study, we included 101 patients with HNSCC (oral cavity, pharynx, and larynx) who were aged ≥ 18 years, had stage III to IVB disease, had a Karnofsky Performance Status ≥ 80, and were deemed fit for CCRT. DNA extraction was done through polymerase chain reaction, and the genotypes of XRCC1 polymorphism were detected using designed restriction fragment length polymorphism. The genetic polymorphisms were classified into wild and polymorphic variants (Arg194Trp CT and TT). Radiation therapy was delivered with conventional parallel opposed lateral and low anterior neck fields with concurrent weekly cisplatin, 35 mg/m2. Acute toxicity was graded per Radiation Therapy Oncology Group criteria, and treatment response was assessed per World Health Organization criteria. Overall survival and progression-free survival (PFS) were estimated using the Kaplan-Meier method. RESULTS: Of the patients, 62 had the wild type and 39 had polymorphic variants. Patients with polymorphic variants had higher rates of grade > 2 oral mucositis, with 35.8% versus 16.0% (odds ratio [OR], 2.91; 95% confidence interval [CI], 1.13-7.46; P = .023); dermatitis, with 30.7% versus 8.0% (OR, 5.076; 95% CI, 1.62-15.8; P = .003); and laryngeal toxicity, with 25.6% versus 6.4% (OR, 5; 95% CI, 1.44-17.54; P = .006). Complete response rates in polymorphic versus wild variants were 76.9% versus 56.0% (P = .209). At a median follow-up of 21 months, the 2-year PFS and overall survival rates for patients with polymorphic versus wild variants were 57.0% versus 42.2% (P = .077) and 73.0% versus 55.5% (P = .143), respectively. CONCLUSIONS: Polymorphic variant XRCC1 HNSCC patients treated with CCRT have significantly increased acute radiation morbidities and may have a trend toward better PFS in comparison with the wild variant.

Prospective evaluation of Intensity Modulated Radiation Therapy with Simultaneous Integrated Boost (IMRT-SIB) in head and neck squamous cell carcinoma in patients not suitable for chemo-radiotherapy.

BACKGROUND: With conformal radiotherapy techniques, acute and late toxicities can be reduced because of better dose conformity and reduced doses to normal tissue. With Intensity Modulated Radiation Therapy (IMRT) further dose escalation is possible and one of the methods is IMRT with simultaneous integrated boost (IMRT-SIB). AIM: To evaluate feasibility, toxicity patterns and loco-regional control rates of IMRT-SIB technique in head and neck cancer patients who are not suitable candidates for concurrent chemoradiation. STUDY DESIGN: Prospective study of 30 patients treated with IMRT-SIB technique and evaluation of clinical results. METHOD AND MATERIALS: 30 patients received definitive treatment using IMRT-SIB without concurrent chemotherapy. Patients were monitored during and after treatment for toxicity using the Radiation Therapy Oncology group (RTOG) criteria. Analysis of acute and late toxicity and early efficacy is presented. RESULTS: The median treatment duration was 42days (range 41-43days). Overall, maximum acute Grade 3 toxicity of mucositis, skin, pharynx/esophageal toxicity and laryngeal were 56.66%, 30%, 26.67%, and 6.67% respectively at treatment completion. None of the patients had Grade 4 acute toxicity. No haematological toxicity was seen. Overall, grade 2 late toxicities were 7% (subcutaneous toxicity) and 13.3% (Xerostomia). Loco regional control rate at a median follow up of 13months was 86%. CONCLUSION: IMRT-SIB is a safe and acceptable treatment option for patients of head and neck squamous cell carcinoma unsuitable for definitive chemo-radiotherapy.

Radiochromic film dosimetry of rectal inhomogeneity and applicator attenuation in high dose rate brachytherapy of uterine cervix.

Heterogeneities existing in the patient during treatment are neglected, as the treated subject is considered homogeneous in most of the commercially-available treatment planning systems (TPSs) used for high dose rate (HDR) brachytherapy. The choice of a suitable dosimeter for experimental dosimetry near the HDR source is crucial, mainly due to existence of steep dose gradients. The present work aimed to assess the effect of rectal air heterogeneity and applicator attenuation in the HDR Ir-192 brachytherapy treatment of carcinoma uterine cervix by utilizing GAFCHROMIC EBT2 film dosimetry. The dose to rectal walls under the condition of rectal air heterogeneity was measured experimentally using EBT2 film in a rectal phantom, and the measurements were validated by the Monte Carlo (MC) simulations. The applicator attenuation was measured by EBT2 film for a commonly used stainless steel uterine tube in a homogeneous water equivalent phantom. The measured doses were compared with the TPS calculated values. In case of the air cavity, the measured dose at the closest rectal surface was 12.8% less than the TPS calculated value due to lack of back scattering, whereas at the farthest rectal surface, it was higher by 24.5% due to no attenuation. The magnitude of attenuation due to the metal applicator was measured as high as 2% when compared with the TPS calculation. The dose reduction at the nearest rectal surface due to the effect of rectal air has indicated a clinically favorable dose distribution within the rectum, whereas the shielding effect posed by the metallic applicator was found to be less significant. Mutual agreement of the measured doses with the MC calculated dose values confirmed the suitability of EBT2 film for clinical dosimetry in HDR brachytherapy.

Unusual double four-lobe textures generated by the motion of carbon nanotubes in a nematic liquid crystal.

Unusual double four-lobe nematic liquid crystal (LC) textures were observed in the carbon nanotube (CNT)-doped nematic LC under electric field. Through the electro-optical studies in a wide range of vertical electric fields in the direction of the long axis of the LC molecules, it was realized that the double four-lobe nematic LC textures were formed in the range of 120 to 160 V(rms) at 1 Hz. The formation of these unusual double four-lobe nematic LC textures could originate from the electric field-induced movement of CNTs and the subsequently frustrated reorientation of LCs.